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When should we use mutex and when should we use semaphore
... to sleep till you release the mutex.
Spinlock:
Use a spinlock when you really want to use a mutex but your thread is not allowed to sleep.
e.g.: An interrupt handler within OS kernel must never sleep. If it does the system will freeze / crash. If you need to insert a node to globally shared linke...
mysql check collation of a table
...
The above answer is great, but it doesn't actually provide an example that saves the user from having to look up the syntax:
show table status like 'test';
Where test is the table name.
(Corrected as per comments below.)
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Javascript checkbox onChange
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Here's a JsFiddle where all the different ways can be tested: click, keyboard, label and accesskey. They all trigger the event in Firefox.
– Roman Starkov
May 8 '15 at 12:59
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What is the difference between `after_create` and `after_save` and when to use which?
... readers should note that, according to the docs, ActiveRecord's update_all does not invoke any callbacks, including after_*
– user2426679
Jan 10 at 19:34
add a comment
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Long press gesture on UICollectionViewCell
...ILongPressGestureRecognizer *lpgr
= [[UILongPressGestureRecognizer alloc]
initWithTarget:self action:@selector(handleLongPress:)];
lpgr.delegate = self;
lpgr.delaysTouchesBegan = YES;
[self.collectionView addGestureRecognizer:lpgr];
}
-(void)handleLongPress:...
std::wstring VS std::string
... on a wchar_t.
char vs. wchar_t
char is supposed to hold a character, usually an 8-bit character.
wchar_t is supposed to hold a wide character, and then, things get tricky:
On Linux, a wchar_t is 4 bytes, while on Windows, it's 2 bytes.
What about Unicode, then?
The problem is that neither char ...
SHFileOperation函数总结（文件夹的移动、复制、删除） - C/C++ - 清泛网 -...
...I SHFileOperation(LPSHFILEOPSTRUCT lpFileOp);
参数：
typedef struct _SHFILEOPSTRUCT
{
HWND hwnd; //父窗口句柄
UINT wFunc; //要执行的动作
LPCTSTR pFrom; //源文件路径，可以是多个文件
LPCTSTR ...
How to cancel an $http request in AngularJS?
...efer();
$http.get('/someUrl', {timeout: canceler.promise}).success(successCallback);
// later...
canceler.resolve(); // Aborts the $http request if it isn't finished.
share
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improve this answer
...
Allow user to select camera or gallery for image
...e));
yourIntentsList.add(finalIntent);
}
List<ResolveInfo> listGall = packageManager.queryIntentActivities(gallIntent, 0);
for (ResolveInfo res : listGall) {
final Intent finalIntent = new Intent(gallIntent);
finalIntent.setComponent(new ComponentName(res.activityInfo.packageName,...
When should I make explicit use of the `this` pointer?
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Usually, you do not have to, this-> is implied.
Sometimes, there is a name ambiguity, where it can be used to disambiguate class members and local variables. However, here is a completely different case where this-> is e...